WebM to MP4
WebM is the video format of screen recorders and many websites, and some phones, editors and upload forms will not take it. Turn WebM files into MP4. Everything happens on your own device, using the video engine built into your browser, so your video is never uploaded.
How to use it
- Choose Play everywhere (recommended) or Keep the original video.
- Choose your WebM videos, or drag them onto the box.
- Download each MP4, or all of them together as a ZIP file.
How it works
WebM files usually hold VP9 or VP8 video with Opus sound. With Play everywhere, the video is converted to H.264 and the sound to AAC, which every device plays. Keep the original video moves VP9 video into the MP4 unchanged, which is faster but plays on fewer devices.
What is kept
The main video and its sound are kept. Subtitles and any extra sound tracks, such as a second language, are left out, and the result says when this has happened.
Limits
Videos are converted in the browser's memory, so very large files are refused before anything starts; the page shows the largest size tested on your kind of device. Long videos take a while, and the page must stay open and on screen while it works, particularly on a phone.
The page reads what is inside each file before it starts. Dolby Digital (AC-3) sound, which many camcorders use, is read by FilePresto's own converter, on your device. A few formats cannot be converted yet: WMV videos, and Dolby Digital Plus (E-AC-3) and DTS sound. If a file has sound that cannot be read, the page stops and says so, rather than making a silent video; you can then choose to convert the video without its sound.
Questions
Are my files uploaded?
No. The work happens inside your web browser, on your own device. Before your file is opened, this page locks itself: from then on your browser refuses to let it fetch, upload or send anything at all. You can check: once the page has loaded, switch off your internet connection and it will still work. How the lock works.